As an example, in colorectal [8], breast [9], and pancreatic [10] cancers, TP53 mutation is marked as a late stage tumourigenic event aiding more with tumour progression than with tumour initiation, while in pre-malignant breast lesions [11], hepatocellular carcinoma [12], and in astrocytoma [13] TP53 mutations present during the early stages of tumorigenesis. The gene discussed is TP53; the disease is astrocytoma (excluding glioblastoma).